So far the only cons refer to low THs getting stuck, having been oblivious of a lock-in to champs.
(Still an exceedingly small group imo) but this could be fixed, with the lock-in to champions league for TH10 (and 9) only.
I, however, think this might be more problematic for players who visited champions before and then suddenly cannot go back down any more, because by then they'd have upgraded their TH to lvl 10 (or 9).
